import request from '@/utils/request'

import html2canvas from 'html2canvas';
import JsPDF from 'jspdf';

export default {
    list(query) {
        return request({
            url: '/labbooking/table/list',
            method: 'get',
            params: query
        })
    },
    
    getTableDetails(labId) {
        return request({
            url: `/labbooking/table/get/${labId}`,
            method: 'get',
        })
    },

    applyTableList(labId, year, term) {
        return request({
            url: `/labbooking/table/applyTableList/${labId}/${year}/${term}`,
            method: 'get'
        })
    },

    appliedTableList(labId, year, term) {
        return request({
            url: `/labbooking/table/appliedTableList/${labId}/${year}/${term}`,
            method: 'get'
        })
    },

    downloadImg(ele, imgName) {
        html2canvas(ele, {
            dpi: 300
        }).then(canvas => {
            let dataURL = canvas.toDataURL('image/png')
            if (dataURL !== '') {
                let alink = document.createElement('a')
                alink.href = dataURL
                alink.download = imgName + '.png'
                alink.click()
            }
        })
    },

    downloadPDF(ele, pdfName) {
        window.scrollTo(0, 0);
        let eleW = ele.offsetWidth;// 获得该容器的宽
        let eleH = ele.offsetHeight;// 获得该容器的高
        let eleOffsetTop = ele.offsetTop;  // 获得该容器到文档顶部的距离
        let eleOffsetLeft = ele.offsetLeft; // 获得该容器到文档最左的距离

        var canvas = document.createElement("canvas");
        var abs = 0;

        let win_in = document.documentElement.clientWidth || document.body.clientWidth; // 获得当前可视窗口的宽度（不包含滚动条）
        let win_out = window.innerWidth; // 获得当前窗口的宽度（包含滚动条）

        if (win_out > win_in) {
            // abs = (win_o - win_i)/2;    // 获得滚动条长度的一半
            abs = (win_out - win_in) / 2;    // 获得滚动条宽度的一半
            // console.log(a, '新abs');
        }
        canvas.width = eleW * 2;    // 将画布宽&&高放大两倍
        canvas.height = eleH * 2;

        var context = canvas.getContext("2d");
        context.scale(2, 2);
        context.translate(-eleOffsetLeft - abs, -eleOffsetTop);
        // 这里默认横向没有滚动条的情况，因为offset.left(),有无滚动条的时候存在差值，因此
        // translate的时候，要把这个差值去掉

        // html2canvas(element).then( (canvas)=>{ //报错
        // html2canvas(element[0]).then( (canvas)=>{
        html2canvas(ele, {
            dpi: 300,
            // allowTaint: true,  //允许 canvas 污染， allowTaint参数要去掉，否则是无法通过toDataURL导出canvas数据的
            useCORS: true  //允许canvas画布内 可以跨域请求外部链接图片, 允许跨域请求。
        }).then((canvas) => {
            var contentWidth = canvas.width;
            var contentHeight = canvas.height;
            //一页pdf显示html页面生成的canvas高度;
            var pageHeight = contentWidth / 595.28 * 841.89;
            //未生成pdf的html页面高度
            var leftHeight = contentHeight;
            //页面偏移
            var position = 0;
            //a4纸的尺寸[595.28,841.89]，html页面生成的canvas在pdf中图片的宽高
            var imgWidth = 595.28;
            var imgHeight = 595.28 / contentWidth * contentHeight;
            var pageData = canvas.toDataURL('image/jpeg', 1.0);
            var pdf = new JsPDF('', 'pt', 'a4');
            //有两个高度需要区分，一个是html页面的实际高度，和生成pdf的页面高度(841.89)
            //当内容未超过pdf一页显示的范围，无需分页
            // console.log('处理完画布高度：' + contentHeight)
            // console.log('每页高度：' + pageHeight)
            if (leftHeight < pageHeight) {
                //在pdf.addImage(pageData, 'JPEG', 左，上，宽度，高度)设置在pdf中显示；
                pdf.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight);
                // pdf.addImage(pageData, 'JPEG', 20, 40, imgWidth, imgHeight);
            } else { // 分页
                while (leftHeight > 10) {
                    // console.log(leftHeight)
                    pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight);
                    leftHeight -= pageHeight;
                    position -= 841.89;
                    //避免添加空白页
                    if (leftHeight > 10) {
                        pdf.addPage();
                    }
                }
            }
            pdf.save(pdfName);
        })
    }
}